The Penduline Tit uses a hidden opening to enter its nest while the visible opening leads to an empty pocket to trick snakes

These skillful architects build pear-shaped nests on the branches of willow or birch trees. First, the male begins the construction of the nest by attaching plant fibers and fluffy seeds to the twigs and branches. Then, with the help of the female, they vow the other parts of the pouch-like nest with spiderweb, wool, animal hair, and other soft plant material. The result is a very elaborate nest that is suspended from the tree.